There’s a critical security flaw in the wild right now that affects the software running a large portion of the modern web. If your organization runs Node.js, Bun, Envoy Proxy, or Istio anywhere in your stack, this needs attention today, not next sprint.
The vulnerability is tracked as CVE-2026-111497 and researchers are calling it Broccoli2Shell. It lives in Brotli, a compression library originally developed by Google that nearly every modern web server and API gateway supports. Brotli is the technology that shrinks HTTP traffic to make pages and API responses load faster. It’s everywhere.
The flaw is an out-of-bounds write in the Brotli decompressor. When a vulnerable system processes specially crafted compressed data from an attacker, the decoder writes data beyond the memory it was allocated. That kind of memory corruption can crash your application, expose sensitive data from adjacent memory, or in the worst case, allow an unauthenticated remote attacker to execute arbitrary code on your server. Researchers at Imperva’s Red Team have already demonstrated successful exploitation against unpatched Node.js environments.
The scope here is what makes this urgent. Wiz’s cloud telemetry shows 91% of cloud environments have at least one vulnerable resource. 82% have publicly exposed Node.js instances. Brotli is embedded in runtime environments, container base images, reverse proxies, and service meshes throughout the typical cloud stack. An application that never explicitly calls Brotli may still be vulnerable if a framework or HTTP client enables it automatically on incoming requests.
The affected versions span every major runtime in the ecosystem. Node.js 22, 24, and 26 are all vulnerable until the patched releases 22.23.4, 24.22.1, and 26.12.1 respectively. Bun is affected through version 1.4.3, with 1.4.4 containing the fix. Envoy Proxy and Istio both have patched releases available from their security advisories. Python packages using the underlying Brotli C decoder are also in scope.
Patching is the only real solution. Disabling Brotli decompression can reduce your exposure as a short-term measure, but it breaks HTTP compression for many clients and should not replace updating. The critical step for containerized workloads is rebuilding from patched base images and redeploying. Simply updating a package manager dependency will not catch copies of the library that were statically linked at build time. Those need a full image rebuild.
The vulnerability was discovered by the OpenAI Codex Security team, with exploitability confirmed by Imperva. The quality of both the discovery and the public exploit demonstration means this is being actively studied by attackers.
A three-day-old proof of concept against a vulnerability present in 91% of cloud environments is not something to schedule for next month’s patching window.
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